You could not post a single remark on a forum without someone regarding it as provocative.

since virtually everyone seems to think more DR is better

Virtually everyone ? I thought they were a myth.

but can we have too much Dynamic Range ?

Not as long as tonal detail is maintained. Increasing DR at the expense of tonal detail would be detrimental.

However we need camera makers to provide good blended LDR output from that extra DR.

Can a sensor with a greater DR produce end up producing results that look 'flat' without post processing ?

Yes.

The problem is that the output media do not have the DR of the recorded image.

To maximize the use of DR ( assuming the scene needs it ! ) you have to use pseudo HDR techniques.

One of my favorite cameras, the Fuji S3, had exceptional DR for it's day but had the great advantage that it could produce JPEGs that blended the HDR into a normal DR range JPEG beautifully. You could do it yourself from RAW, but it was really good for JPEGs for that reason.

We do need the makers to provide suitable mechanisms to generate good JPEGs easily.

After all many photographers, especially landscape photographers, used to prefer certain films like Fuji Velvia and that had a quite limited DR.

I think that modern sensors have about 13 EV and really that's more than enough for most scenes in my experience. I think the benefits of DR beyond that are limited and diminishing.

I used to bracket a lot more often for extended DR scenes and HDR blend in software and these days I hardly need to do that with 12+ EV at my disposal.